Internet giant Google has launched an online tracking tool designed to protect world fish stocks by tracking illegal fishing boats.

Vessels plying the oceans with nets that can be as big as a football pitch plunder 26m tonnes of fish each year, scientists estimate depleting fisheries and revenues in countries often too poor to deal with the threat.

But Google has worked with conservation campaign groups to devise a website that will let people easily pinpoint thousands of boats’ movements in near real time so that suspicious looking fishing can be reported to authorities.

“We’re able to bring massive scale and technology to global problems that were not possible to address in the same way just a few years ago and this is one of them,” said Brian Sullivan, the manager in charge of the project at Google, whose technology is already being used to protect African apes, Sumatran tigers and other wildlife.

The US search giant’s ability to manage and store vast amounts of data has made it a target of privacy campaigners. But it could also help tackle the problem of overfishing that now affects nearly a third of the world’s marine fish stocks.

Fishing is banned or restricted in many zones, sometimes to protect fragile ecosystems such as Australia’s Great Barrier Reef, and also because countries earmark waters off their coasts for their own fishing boats.

But it is relatively easy for boats to slip in and out of some of these areas to poach fish undetected because many countries lack the resources to monitor foreign intruders.